Resource selection apparatus and communication system

ABSTRACT

An apparatus and method to select a resource for performing device to device (D2D) communication from a resource pool configured in a second mode by a first eNB.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication PCT/CN2014/077148 filed on May 9, 2014, the entire contentsof which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to the field of communications, and inparticular to a resource selection apparatus and communication system.

BACKGROUND ART

Device to device (D2D) communication refers to that data packets neednot to pass through a core network, even need not to pass through aneNB, and a communication link is established directly between two piecesof UE (UE1 and UE2) for performing communication. FIG. 1 is a schematicdiagram of establishing D2D communication between two pieces of UEbelonging to the same eNB, and FIG. 2 is a schematic diagram ofestablishing D2D communication between two pieces of UE belonging todifferent eNBs.

Before UE performs D2D direct communication, an eNB need to allocate acommunication resource for the UE. And a mode for allocating a D2Dcommunication resource by the eNB includes a mode 1 and a mode 2.

A resource allocation scheme of mode 1: which is an allocation schemescheduled by the eNB; before the eNB schedules the resource of mode 1,the UE needs to enter into a radio resource control (RRC) connectedstate (RRC_Connected state), and transmits a resource request to the eNBby means of a buffer state report (BSR), etc. After receiving therequest, the eNB allocates a resource for the UE.

A resource allocation scheme of mode 2: the eNB notifies the UE of atime-frequency location of the resource pool via broadcast or specificsignaling. When the UE is not covered by the eNB, the resource pool ofmode 2 is preconfigured in the UE. After obtaining the resource pool,the UE may select a resource for D2D communication from the resourcepool on its own.

It should be noted that the above description of the background art ismerely provided for clear and complete explanation of the presentinvention and for easy understanding by those skilled in the art. And itshould not be understood that the above technical solution is known tothose skilled in the art as it is described in the background art of thepresent invention.

SUMMARY

For UE not covered by an eNB, the resource of mode 2 may only be used.However, for UE that can use both the resource allocation modes, thereexists no method for solving a problem that a resource of which mode isselected.

In order to solve the above problem, embodiments of the presentinvention provide a resource selection apparatus and communicationsystem. With the apparatus, the UE is facilitated to select acorresponding resource for communication, so as to ensure continuity ofthe D2D communication, and avoid disconnection.

According to a first aspect of the embodiments of the present invention,there is provided a resource selection apparatus, including:

a first selection unit configured to select a resource for performingdevice to device (D2D) communication from a resource pool configured ina second mode by a first eNB or a second eNB after user equipment (UE)is disconnected from the first eNB, in a first period from the UEreceives physical layer out-of-synchronization indication information tothe UE receives a first resource allocated in a first mode by the secondeNB reestablishing a connection with the UE, or in a second period fromthe UE receives configuration information triggering the UE to be handedover to the second eNB to the UE receives a first resource allocated ina first mode by the second eNB, or in a third period from the UEinitializes reestablishment to the UE receives a first resourceallocated in a first mode by the second eNB reestablishing a connectionwith the UE, or in a fourth period from the UE transmits areestablishment request to the UE receives a first resource allocated ina first mode by the second eNB reestablishing a connection with the UE.

According to a second aspect of the embodiments of the presentinvention, there is provided a resource selection apparatus, including:

a first transmitting unit configured to transmit a handover request to asecond eNB according to a measurement result transmitted by UE, thehandover request comprising information on that the UE is performing D2Dcommunication, and/or an allocation mode and a resource location of aD2D communication resource used by the UE;

a first receiving unit configured to receive configuration informationfed back by the second eNB according to the handover request, theconfiguration information comprising a time-frequency location of aresource pool configured in a second mode by the second eNB, and/orinformation indicating whether the second eNB supports a resourceallocation scheme in a first mode, and/or a resource location of aresource allocated in the first mode by the second eNB; and

a first configuring unit configured to configure the configurationinformation for the UE.

According to a third aspect of the embodiments of the present invention,there is provided a communication system, including a first eNB, asecond eNB and UE, wherein,

after the UE is disconnected from the first eNB, the UE selects aresource for performing device to device (D2D) communication from aresource pool configured in a second mode by a first eNB or a secondeNB, in a first period from the UE receives physical layerout-of-synchronization indication information to the UE receives a firstresource allocated in a first mode by the second eNB reestablishing aconnection with the UE, or in a second period from the UE receivesconfiguration information triggering the UE to be handed over to thesecond eNB to the UE receives a first resource allocated in a first modeby the second eNB, or in a third period from the UE initializesreestablishment to the UE receives a first resource allocated in a firstmode by the second eNB reestablishing a connection with the UE, or in afourth period from the UE transmits a reestablishment request to the UEreceives a first resource allocated in a first mode by the second eNBreestablishing a connection with the UE.

An advantage of the embodiments of the present invention exists in thatthe UE may use the resource selected from the resource pool configuredby the first eNB or the second eNB in the second mode for communicationin a prescribed period, so that the UE is facilitated to select acorresponding resource for the D2D communication when the UE is in ascenario of handover or failure reestablishment, etc, so as to ensurecontinuity of the D2D communication, and avoid disconnection.

With reference to the following description and drawings, the particularembodiments of the present invention are disclosed in detail, and theprinciple of the present invention and the manners of use are indicated.It should be understood that the scope of the embodiments of the presentinvention is not limited thereto. The embodiments of the presentinvention contain many alternations, modifications and equivalentswithin the spirits and scope of the terms of the appended claims.

Features that are described and/or illustrated with respect to oneembodiment may be used in the same way or in a similar way in one ormore other embodiments and/or in combination with or instead of thefeatures of the other embodiments.

It should be emphasized that the term“comprises/comprising/includes/including” when used in thisspecification is taken to specify the presence of stated features,integers, steps or components but does not preclude the presence oraddition of one or more other features, integers, steps, components orgroups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are included to provide further understanding of thepresent disclosure, which constitute a part of the specification andillustrate the preferred embodiments of the present disclosure, and areused for setting forth the principles of the present disclosure togetherwith the description. It is obvious that the accompanying drawings inthe following description are some embodiments of the present disclosureonly, and a person of ordinary skill in the art may obtain otheraccompanying drawings according to these accompanying drawings withoutmaking an inventive effort. In the drawings:

FIG. 1 is a schematic diagram of establishing D2D communication betweentwo pieces of UE belonging to the same eNB;

FIG. 2 is a schematic diagram of establishing D2D communication betweentwo pieces of UE belonging to different eNBs;

FIG. 3 is a flowchart of the resource selection method of Embodiment 1of the present invention;

FIGS. 4A and 4B are flowcharts of the resource selection method ofEmbodiment 2 of the present invention;

FIGS. 5A and 5B are flowcharts of the resource selection method ofEmbodiment 3 of the present invention;

FIG. 6 is a schematic diagram of a structure of the resource selectionapparatus of Embodiment 4 of the present invention;

FIG. 7 is a schematic diagram of a structure of the UE of Embodiment 5of the present invention;

FIG. 8 is a schematic diagram of a structure of the resource selectionapparatus of Embodiment 6 of the present invention;

FIG. 9 is a schematic diagram of a structure of the eNB of Embodiment 7of the present invention;

FIG. 10 is a schematic diagram of a structure of the eNB of Embodiment 8of the present invention; and

FIG. 11 is a schematic diagram of a structure of the communicationsystem of Embodiment 9 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

These and further aspects and features of the present invention will beapparent with reference to the following description and attacheddrawings. In the description and drawings, particular embodiments of theinvention have been disclosed in detail as being indicative of some ofthe ways in which the principles of the invention may be employed, butit is understood that the invention is not limited correspondingly inscope. Rather, the invention includes all changes, modifications andequivalents coming within the spirit and terms of the appended claims.Various embodiments of the present invention shall be described belowwith reference to the accompanying drawings.

Embodiment 1

Embodiment 1 of the present invention provides a resource selectionmethod. FIG. 3 is a flowchart of the method. Referring to FIG. 3, themethod includes:

Step 301: selecting, by UE, a resource for performing device to device(D2D) communication from a resource pool configured in a second mode bya first eNB or a second eNB after the UE is disconnected from the firsteNB, in a first period from the UE receives physical layerout-of-synchronization indication information to the UE receives a firstresource allocated in a first mode by the second eNB reestablishing aconnection with the UE, or in a second period from the UE receivesconfiguration information triggering the UE to be handed over to thesecond eNB to the UE receives a first resource allocated in a first modeby the second eNB, or in a third period from the UE initializesreestablishment to the UE receives a first resource allocated in a firstmode by the second eNB reestablishing a connection with the UE, or in afourth period from the UE transmits a reestablishment request to the UEreceives a first resource allocated in a first mode by the second eNBreestablishing a connection with the UE.

In this embodiment, the first resource allocated in the first mode bythe eNB may be a resource allocated in an allocation scheme scheduled bythe eNB, which may be referred to as a resource of mode 1; the resourcepool configured by the eNB in the second mode may be referred to as aresource pool of mode 2; and the UE selects the resource for D2Dcommunication from the resource pool, the first mode and the second modecorresponding to mode 1 and mode 2 described in the Background Art.

It can be seen from the above embodiment that when the UE isdisconnected from one eNB and is connected to another eNB, beforereceiving the first resource allocated by the other eNB in the firstmode, the UE selects the resource for performing D2 communication fromthe resource pool configured by the above eNB in the second mode, so asto ensure continuity of the D2D communication, and avoid disconnection.

In this embodiment, in a scenario of handover, the first eNB may be asource eNB, and the second eNB may be a target eNB; or in a scenario offailure reestablishment, the first eNB is an eNB where is UE is presentwhen failure occurs in the UE, and the second eNB is an eNBreestablishing a connection with the UE, which may be the first eNB, andmay also be another eNB.

For example, for the failure reestablishment scenario,

a failure occurs in the UE, and the UE is disconnected from the firsteNB, triggers an initialization reestablishment process, selects anappropriate cell and reestablishesa connection to an eNB of the cell,such as the second eNB. Wherein, the initialization reestablishmentprocess may be triggered when a radio link failure (RLF), a handoverfailure, an eNB reconfiguration failure, or an underlying integritycheck failure occurs.

In this embodiment, when the failure of triggering the initializationreestablishment process is a radio link failure (RLF), the UE selectsthe resource for D2D communication from the resource pool configured bythe first eNB or the second eNB in the second mode in the first period(T1) from the UE receives the physical layer out-of-synchronizationindication information to the UE receives the first resource allocatedin the first mode by the second eNB reestablishing a connection with theUE, but does not use the first resource configured by the eNB in thefirst mode.

In this embodiment, when the failure of triggering the initializationreestablishment process is a handover failure, the UE selects theresource for D2D communication from the resource pool configured by thefirst eNB or the second eNB in the second mode in the second period (T2)from the UE receives the configuration information triggering the UE tobe handed over to the second eNB to the UE receives the first resourceallocated in the first mode by the second eNB, but does not use thefirst resource configured by the eNB in the first mode.

In this embodiment, when the failure of triggering the initializationreestablishment process is an eNB reconfiguration failure, an underlyingintegrity check failure, or a handover failure, the UE selects theresource for D2D communication from the resource pool configured by thefirst eNB or the second eNB in the second mode in the third period (T3)from the UE initializes the reestablishment to the UE receives the firstresource allocated in the first mode by the second eNB reestablishing aconnection with the UE, but does not use the first resource configuredby the eNB in the first mode.

In this embodiment, when the failure of triggering the initializationreestablishment process is a handover failure, the UE selects theresource for D2D communication from the resource pool configured by thefirst eNB or the second eNB in the second mode in the fourth period (T4)from the UE transmits the reestablishment request to the UE receives thefirst resource allocated in the first mode by the second eNBreestablishing a connection with the UE, but does not use the firstresource configured by the eNB in the first mode.

For example, for the handover scenario,

after the UE receives the configuration information triggering the UE tobe handed over to the second eNB, the UE is disconnected from the firsteNB, and establishes a connection with the second eNB via a randomaccess process.

The UE selects the resource for D2D communication from the resource poolconfigured by the first eNB or the second eNB in the second mode in thesecond period (T2) from the UE receives the configuration informationtriggering the UE to be handed over to the second eNB to the UE receivesthe first resource allocated in the first mode by the second eNB, butdoes not use the first resource configured by the eNB in the first mode.

It can be seen from the resource selection method of this embodimentthat the UE may use the resource selected from the resource poolconfigured by the first eNB or the second eNB in the second mode forcommunication in the first period, the second period, the third periodor the fourth period, which facilitates the UE to select a correspondingresource for the D2D communication in a handover or a failurereestablishment scenario, so as to ensure continuity of the D2Dcommunication.

In this embodiment, in the first period, the second period, the thirdperiod or the fourth period, the UE may either select a resource in theresource pool configured by the first eNB, or select a resource in theresource pool configured by the second eNB; and furthermore, it mayselect a resource in a manner as follows:

after receiving the resource pool configured by the second eNB in thesecond mode, the UE selects the resource for D2D communication from theresource pool configured by the second eNB; and before receiving theresource pool configured by the second eNB in the second mode, the UEselects the resource for D2D communication from the resource poolconfigured by the first eNB in the second mode.

For example, when the UE performs inter-cell handover, it may use theresource pool of mode 2 configured by the source eNB or the target eNB;or after receiving the resource pool configured by the target eNB, theUE selects the resource for D2D communication from the resource poolconfigured by the target eNB; and before receiving the resource poolconfigured by the target eNB, the UE selects the resource for D2Dcommunication from the resource pool configured by the source eNB.

For example, when the UE performs failure reestablishment, it may usethe resource pool of mode 2 configured by the eNB where the UE ispresent when the failure occurs or the eNB to which a connection isreestablished by the UE; or after receiving the resource pool of mode 2configured by the eNB to which a connection is reestablished by the UE,the UE selects the resource for communication from the resource poolconfigured by the eNB to which a connection is reestablished by the UE;and before receiving the resource pool of mode 2 configured by the eNBto which a connection is reestablished by the UE, the UE selects theresource for D2D communication from the resource pool configured by theeNB where the UE is present when the failure occurs.

In this embodiment, as shown in FIG. 3, the method further includes:

Step 302: releasing the resource pool after the UE receives the firstresource allocated in the first mode by the second eNB, or when the UEreceives from the second eNB indication information indicating the UE touse the first resource.

Wherein, after the UE is connected to the second eNB and receives theindication information, the UE terminates use of the resource of mode 2,releases the resource pool of mode 2, request the second eNB for thefirst resource, and uses the first resource after obtaining the firstresource allocated by the eNB.

The above resource pool may include the resource pool configured by thefirst eNB and/or the second eNB in the second mode.

For example, when the UE performs inter-cell handover, after the UEreceives the resource of mode 1 allocated by the target eNB, the MAClayer will be configured with the resource of mode 1, and at the sametime, the resource of mode 2 will be released; or, when the UE receivesthe indication information of the target eNB indicating the UE to usethe resource of mode 1, the UE terminates use of the resource of mode 2,releases the resource pool of mode 2, and requests the target eNB forthe resource of mode 1.

For example, when the UE performs failure reestablishment, after the UEreceives the resource of mode 1 allocated by the eNB to which aconnection is reestablished by the UE, the MAC layer will be configuredwith the resource of mode 1, and at the same time, the resource of mode2 will be released; or, when the UE receives the indication informationof the eNB to which a connection is reestablished by the UE indicatingthe UE to use the resource of mode 1, the UE terminates use of theresource of mode 2, releases the resource pool of mode 2, and requeststhe eNB to which a connection is reestablished by the UE for theresource of mode 1.

In this embodiment, if a time used by the UE in succeeding in handoveris relatively short, in a relatively short process of handover, it ispossible that the resource pool configured in the second mode is notused. Hence, the method may further include: when the UE is handed overto the second eNB unsuccessfully within a first predetermined timestarting from the UE receives the configuration information, the secondperiod includes a period from exceeding the first predetermined timeuntil the first resource is received; wherein, the first predeterminedtime is shorter than a time from the UE receives the configurationinformation to succeeding in being connected to the second eNB.

In this embodiment, if a time used by the UE in a reestablishmentprocess is relatively short, in a relatively short reestablishmentprocess, it is possible that the resource pool configured in the secondmode is not used. Hence, the method may further include: when the UEdoes not select an appropriate cell in a second predetermined timestarting from initializing the reestablishment, the third periodincludes a period from exceeding the second predetermined time until thefirst resource is received; wherein, the second predetermined time isshorter than a time starting from initializing reestablishment to thatan appropriate cell is selected.

In this embodiment, before the UE performs handover and is disconnectedfrom the first eNB, the method may further includes: receiving theconfiguration information configured by the first eNB.

Wherein, the configuration information includes: a time-frequencylocation of the resource pool configured in the second mode by thesecond eNB, and/or information indicating whether the second eNBsupports a resource allocation scheme in the first mode, and/or aresource location of a resource allocated in the first mode by thesecond eNB.

In this embodiment, when the UE performs handover, the first eNB maytransmit a handover request to the second eNB according to a measurementresult transmitted by the UE, the handover request including informationon that the UE is performing D2D communication, and/or an allocationmode and a resource location of a D2D communication resource used by theUE; after receiving the configuration information fed back by the secondeNB according to the handover request, the first eNB configures the UEwith the configuration information, this is a reconfiguration process.

It can be seen from the resource selection method of this embodimentthat the UE may use the resource selected from the resource poolconfigured by the first eNB or the second eNB in the second mode forcommunication in a prescribed period, which facilitates the UE to selecta corresponding resource for the D2D communication in a handover or afailure reestablishment scenario.

The resource selection method shall be described in detail taking ahandover scenario and a failure reestablishment scenario as examples,respectively.

Embodiment 2

Embodiment 2 of the present invention provides a resource selectionmethod, regarding an implementation scenario where the UE performsinter-cell handover. The method includes: selecting by the UE a resourcefor performing D2D communication from a resource pool configured in asecond mode by a source eNB or a target eNB after the UE is disconnectedfrom the source eNB, in a second period from the UE receivesconfiguration information triggering the UE to be connected to thetarget eNB to the UE receives a first resource allocated in a first modeby the target eNB.

In this embodiment, implementations of the first resource allocated inthe first mode and the resource pool configured in the second mode areidentical to those in Embodiment 1, and shall not be described hereinany further.

FIG. 4A is a flowchart of the resource selection method of Embodiment 2.For a handover scenario, referring to FIG. 4A, the method includes:

Step 401: notifying a time-frequency position of the resource pool ofmode 2 configured by the source eNB to the UE by the source eNB, andnotifying the UE that it may use the resource of mode 1;

in this embodiment, the source eNB notifies the time-frequency positionof the resource pool of mode 2 to the UE via broadcast or specificsignaling, and/or the source eNB notify the UE via broadcast or specificsignaling that it may apply for using the resource of mode 1.

Step 402: reporting a measurement result by the UE;

in this embodiment, the UE measures channel quality, such as referencesignal receiving power (RSRP) and reference signal receiving quality(RSRQ), and report the measurement result to the source eNB.

Step 403: transmitting a handover request to the target eNB by thesource eNB according to the measurement result;

in this embodiment, the handover request may include information on thatthe UE is performing D2D communication, and/or an allocation mode and aresource location of a D2D communication resource used by the UE.

Step 404: transmitting the configuration information to the source eNBby the target eNB after receiving the handover request;

in this embodiment, the configuration information may include thetime-frequency position of the resource pool configured by the targeteNB in mode 2, and/or information on whether the target eNB supports theresource allocation scheme in mode 1, and/or a resource location of aresource allocated in mode 1 by the target eNB.

Step 405: reconfiguring the UE by the source eNB after receiving theconfiguration information of the target eNB;

in this embodiment, the source eNB configures the UE with theconfiguration information;

wherein, any existing manner may be used for a manner of configuration,such as notifying the configuration information to the UE via high-layersignaling or other signaling.

Step 406: establishing a connection with the target eNB; wherein, in thesecond period from the UE receives the configuration information to theUE receives the resource allocated in mode 1 by the target eNB, the UEselects the resource for D2D communication from the resource poolconfigured by the source eNB or the target eNB in mode 2;

in this embodiment, if the configuration information is configured viaan RRC connection reconfiguration message, when the UE receives an RRCconnection reconfiguration message containing a mobility control InfoIE, it starts a T304 timer for timing, is disconnected from the sourceeNB, and establishes a connection with the target eNB via random access,and the T304 timer terminates the timing.

Step 407: transmitting a resource request by the UE to the target eNB.

Step 408: allocating the first resource by the target eNB to the UE.

Step 409: notifying the allocated resource by the target eNB to the UE,and the UE succeeding in receiving the first resource allocated by thetarget cell.

In this embodiment, in a time period from the T304 timer is started tothe resource of mode 1 allocated by the target cell is successfullyreceived (period T2), the UE selects the resource for D2D communicationfrom the resource pool of mode 2, but does not use the resource of mode1; wherein, an existing standard may be referred to for a particularsetting method of T304, which shall not be described herein any further.

In an implementation, the UE may further set a first timer. In step 406,when the UE receives an RRC connection reconfiguration messagecontaining a mobility control Info IE, it may start a first timer (T1′)while starting the T304 timer. At a time period from the first timerexpires to the resource of mode 1 allocated by the target eNB issuccessfully received (a time period T2′), the UE selects the resourcefor D2D communication from the resource pool of mode 2, but does not usethe resource of mode 1; wherein, T1′ is less than T304. It can be seentherefrom that when a time needed by the UE in being handed over to thetarget eNB is relatively short, the UE may not take the resource used inT′ into account.

In this embodiment, the UE may use the resource pool of mode 2configured by the source eNB or the target eNB, or the UE may select theresource for D2D communication from the resource pool configured by thetarget eNB after receiving the resource pool of mode 2 configured by thetarget eNB; and the UE may select the resource for D2D communicationfrom the resource pool of mode 2 configured by the source eNB beforereceiving the resource pool of mode 2 configured by the target eNB.

As shown in FIG. 4A, the method further includes:

Step 410: terminating selection of resource for D2D communication fromthe resource pool of mode 2 by the UE after successfully receiving theresource of mode 1 allocated by the target eNB; and

Step 411: releasing the resource pool of mode 2 by the UE afterreceiving the resource of mode 1 allocated by the target eNB;

wherein, after the UE receives the resource of mode 1 allocated by thetarget eNB, the MAC layer will be configured with the resource of mode1, and at the same time, release the resource pool of mode 2.

In another implementation, as shown in FIG. 4B, within the above timeperiods T2 and T2′, after step 406, the UE receives the indicationinformation transmitted by the target eNB indicating the UE to use theresource of mode 1 (see step 406′), terminates use of resource of mode2, releases the resource pool of mode 2 (see steps 410′ and 411′), andrequests the target cell for the resource of mode 1 (see step 407).

In the above embodiment, orders of steps 410 and 411 and orders of steps410′ and 411′ are interchangeable, or may be executed simultaneously.

It can be seen from the resource selection method of this embodimentthat the UE may select the resource for D2D communication from theresource pool of mode 2 after receiving the reconfiguration informationtransmitted by the source eNB in the handover and before receiving theresource of mode 1 allocated by the target cell, so as to ensurecontinuity of D2D communication.

Embodiment 3

Embodiment 3 of the present invention provides a resource selectionmethod, regarding an implementation scenario of failure reestablishmentby the UE. In this embodiment, failures triggering an initializationreestablishment process mainly include: a radio link failure (RLF), ahandover failure, an eNB reconfiguration failure, and an underlyingintegrity check failure, etc.

In this embodiment, implementations of the first resource allocated inthe first mode and the resource pool configured in the second mode areidentical to those of Embodiment 1, which shall not be described hereinany further. And in this embodiment, the second eNB may be the firsteNB, and may also be another eNB.

FIG. 5A is a flowchart of the resource selection method of Embodiment 3.Referring to FIG. 5A, the method includes:

Step 501: notifying a time-frequency position of the resource pool ofmode 2 configured by the first eNB to the UE by the first eNB, andnotifying the UE that it may use the resource of mode 1;

-   -   in this embodiment, similar to step 401, the first eNB may        notify the time-frequency position of the resource pool of mode        2 to the UE via broadcast or specific signaling, and/or the        first eNB notify the UE via broadcast or specific signaling that        it may apply for using the resource of mode 1.

Steps 503-505: triggering the initialization reestablishment process bythe UE after a failure occurs, and transmitting an RRC connectionreestablishment request after selecting an appropriate cell;

in this embodiment, starting from triggering the initializationreestablishment, a timer T311 is started for timing, the appropriatecell is selected, such as a cell of the second eNB, and the timer T311is terminated.

Step 506: receiving by the UE a message of success or failure of the RRCconnection reestablishment fed back by the second eNB;

in this embodiment, when the UE transmits the RRC connectionreestablishment request to the second eNB, the timer T301 may be startedfor timing, and the timer T301 is terminated until the message ofsuccess or failure of the RRC connection reestablishment fed back by thesecond eNB is received;

when a message of success of connection reestablishment is received, theUE establishes a connection with the second eNB; and if a message offailure of connection reestablishment is received, reestablishment ofthe UE fails, but the UE may still execute step 505 to transmit theconnection establishment request and establish a connection with thesecond eNB. Step 507: establishing RRC connection successfully by the UEwith the second eNB;

In this embodiment, a process of establishing the RRC connection issimilar to that in the prior art, which shall be described herein inbrief. First, cell selection is performed; the UE transmits the RRCconnection request to the selected second eNB; the second eNB feeds backthe RRC connection establishment message to the UE after receiving theRRC connection request; after receiving the RRC connection establishmentmessage, the UE transmits an RRC connection establishment completionmessage to the second eNB, thereby successfully establishing theconnection between the UE and the second eNB.

In the above embodiment, the cell selected in the reestablishmentinitialization process in step 503 may be identical to or different fromthe cell selected in step 507, that is, the second eNBs may be identicalor different. Steps 508-512 are similar to steps 407-411 of Embodiment 2shown in FIG. 4A, which shall not be described herein any further.

In this embodiment, for a scenario of a radio link failure, the methodfurther includes:

Step 502: receiving physical layer out-of-synchronization indicationinformation;

wherein, after the physical layer out-of-synchronization indicationinformation is received, the timer T310 may be started for timing, andthe timer T310 is terminated when the physical layer synchronizationindication information has been received, or the handover process istriggered, or the reestablishment initialization process is started.

In the above embodiment, for the radio link failure, the UE selects theresource for D2D communication from the resource pool of mode 2 in theperiod from T310 is started to the UE successfully receives the resourceof mode 1 allocated by the eNB to which a connection is successfullyreestablished (period T1), but does not use the resource of mode 1.

For the scenario of handover failure, similar to the case in Embodiment2, when the UE receives the configuration information configured by thefirst eNB, the timer T304 is started, the UE is handed over to thesecond eNB and the handover fails. After the handover failure, the UEestablishes a connection with the second eNB via the reestablishmentinitialization process and the reestablishment connection process (suchas steps 503-507 shown in FIG. 5). Hence, the UE selects the resourcefor D2D communication from the resource pool of mode 2 in the periodfrom T304 is started to the UE successfully receives the resource ofmode 1 allocated by an eNB (such as the second eNB) of a cell to which aconnection is reestablished (period T2), but does not use the resourceof mode 1.

In step 503, the UE selects the resource for D2D communication from theresource pool of mode 2 in the period from the reestablishmentinitialization is triggered and the timer T311 is started to the UEsuccessfully receives the resource of mode 1 allocated by the cell towhich a connection is reestablished (period T3), but does not use theresource of mode 1.

In step 505, the UE selects the resource for D2D communication from theresource pool of mode 2 in the period from the RRC connectionreestablishment request is transmitted to the UE successfully receivesthe resource of mode 1 allocated by the cell to which a connection isreestablished (period T4), but does not use the resource of mode 1.

For failures resulted from eNB reconfiguration failure, and underlyingintegrity check failure, etc., the UE selects the resource for D2Dcommunication from the resource pool of mode 2 in the period from the UEinitiates the reestablishment initialization process and the timer T311is started to the UE successfully receives the resource of mode 1allocated by the cell to which a connection is reestablished (T3), butdoes not use the resource of mode 1.

In this embodiment, the UE may further set a second timer (T2″), whichis started when the reestablishment initialization is started. In aperiod from the second timer expires to the UE successfully receives theresource of mode 1 allocated by the cell to which a connection isreestablished (T3′), the UE selects the resource for D2D communicationfrom the resource pool of mode 2, but does not use the resource of mode1; wherein, T2″ is less than T311.

In this embodiment, existing standards may be referred to forimplementations of the timers T310, T304, 311 and T301, which shall notbe described herein any further.

In another embodiment, as shown in FIG. 5B, within the above periods T1,T2, T3, T3′ and T4, the UE receives the indication informationtransmitted by the target eNB indicating the UE to use the resource ofmode 1 (see step 507′), terminates use of resource of mode 2, releasesthe resource pool of mode 2 (see steps 511′ and 512′), and requests thetarget cell for the resource mode 1 (see step 508). In the aboveembodiment, orders of steps 511 and 512 and orders of steps 511′ and512′ are interchangeable, or may be executed simultaneously.

In steps 407 and 508 of Embodiment 2 and Embodiment 3, before the UEtransmits the resource request to the target eNB, the method may furtherinclude: judging whether the received configuration information containsthe resource of mode 1; and executing steps 407 and 508 by the UE whenthe configuration information does not contain the resource of mode 1,that is, transmitting a request for the resource of mode 1 to the targeteNB.

In the above embodiment, the UE may use the resource pool of mode 2configured by the eNB in which a failure occurs (the first eNB) or theeNB to which a connection is reestablished (the second eNB); or, afterreceiving the resource pool of mode 2 configured by the eNB to which aconnection is reestablished, the UE selects the resource for D2Dcommunication from the resource pool configured by the eNB to which aconnection is reestablished; and before receiving the resource pool ofmode 2 configured by the eNB to which a connection is reestablished, theUE selects the resource for D2D communication from the resource pool ofmode 2 configured by the eNB in which a failure occurs.

It can be seen from the resource selection method of this embodimentthat the UE may use the resource selected from the resource poolconfigured by the first eNB or the second eNB in the second mode forcommunication in a prescribed period, which facilitates the UE to selecta corresponding resource for the D2D communication in a failurereestablishment scenario, so as to ensure continuity of the D2Dcommunication.

Embodiment 4

Embodiment 4 of the present invention provides a resource selectionapparatus, as described in Embodiment 4 below. As a principle of theresource selection apparatus for solving problems is similar to those ofthe methods of embodiments 1-3, the implementations of the methods ofembodiments 1-3 may be referred to for a particular implementation ofthe apparatus, with identical contents being not going to be describedherein any further.

FIG. 6 is a schematic diagram of a structure of the resource selectionapparatus of Embodiment 4 of the present invention. As shown in FIG. 6,the apparatus 600 includes:

a first selection unit 601 configured to select a resource forperforming device to device (D2D) communication from a resource poolconfigured in a second mode by a first eNB or a second eNB after userequipment (UE) is disconnected from the first eNB, in a first periodfrom the UE receives physical layer out-of-synchronization indicationinformation to the UE receives a first resource allocated in a firstmode by the second eNB reestablishing a connection with the UE, or in asecond period from the UE receives configuration information triggeringthe UE to be handed over to the second eNB to the UE receives a firstresource allocated in a first mode by the second eNB, or in a thirdperiod from the UE initializes reestablishment to the UE receives afirst resource allocated in a first mode by the second eNBreestablishing a connection with the UE, or in a fourth period from theUE transmits a reestablishment request to the UE receives a firstresource allocated in a first mode by the second eNB reestablishing aconnection with the UE.

In this embodiment, the first eNB and the second eNB, and the first modeand second mode for allocating resources, are as described inembodiments 1-3, and shall not be described herein any further.

In this embodiment, when the failure of triggering the initializationreestablishment process by the UE is a radio link failure (RLF), thefirst selection unit 601 selects the resource for D2D communication fromthe resource pool configured by the first eNB or the second eNB in thesecond mode in the first period from the UE receives the physical layerout-of-synchronization indication information to the UE receives thefirst resource allocated in the first mode by the second eNBreestablishing a connection with the UE, but does not use the firstresource configured by the eNB in the first mode.

In this embodiment, when the UE is handed over or the failure oftriggering the initialization reestablishment process by the UE is ahandover failure, the first selection unit 601 selects the resource forD2D communication from the resource pool configured by the first eNB orthe second eNB in the second mode in the second period from the UEreceives the configuration information triggering the UE to be handedover to the second eNB to the UE receives the first resource allocatedin the first mode by the second eNB, but does not use the first resourceconfigured by the eNB in the first mode.

In this embodiment, when the failure of triggering the initializationreestablishment process by the UE is an eNB reconfiguration failure, anunderlying integrity check failure, or a handover failure, the firstselection unit 601 selects the resource for D2D communication from theresource pool configured by the first eNB or the second eNB in thesecond mode in the third period from the UE initializes thereestablishment to the UE receives the first resource allocated in thefirst mode by the second eNB reestablishing a connection with the UE,but does not use the first resource configured by the eNB in the firstmode.

In this embodiment, when the failure of triggering the initializationreestablishment process by the UE is a handover failure, the firstselection unit 601 selects the resource for D2D communication from theresource pool configured by the first eNB or the second eNB in thesecond mode in the fourth period from the UE transmits thereestablishment request to the UE receives the first resource allocatedin the first mode by the second eNB reestablishing a connection with theUE, but does not use the first resource configured by the eNB in thefirst mode.

It can be seen from the resource selection apparatus of this embodimentthat the UE may use the resource selected from the resource poolconfigured by the first eNB or the second eNB in the second mode forcommunication in the first period, the second period, the third periodor the fourth period, which facilitates the UE to select a correspondingresource for the D2D communication in a handover or a failurereestablishment scenario, so as to ensure continuity of the D2Dcommunication.

In this embodiment, the first selection unit 601 selects the resourcefor performing the D2D communication from a resource pool configured ina second mode by the second eNB, after the UE receives the resource poolconfigured in the second mode by the second eNB; and selects theresource for performing the D2D communication from the resource poolconfigured in the second mode by the first eNB, before the UE receivesthe resource pool configured in the second mode by the second eNB.

In an implementation, when the UE performs inter-cell handover, thefirst selection unit 601 may select the resource in the resource pool ofmode 2 configured by the source eNB or the target eNB; or after the UEreceives the resource pool of mode 2 configured by the target eNB, thefirst selection unit 601 selects the resource for D2D communication fromthe resource pool configured by the target eNB; and before the UEreceives the resource pool of mode 2 configured by the target eNB, thefirst selection unit 601 selects the resource for D2D communication fromthe resource pool of mode 2 configured by the source eNB.

In an implementation, when the UE performs failure reestablishment, thefirst selection unit 601 may use the resource pool of mode 2 configuredby the eNB where the failure occurs or the eNB to which a connection isreestablished successfully by the UE; or after the UE receives theresource pool of mode 2 configured by the eNB to which a connection isreestablished successfully by the UE, the first selection unit 601selects the resource for D2D communication from the resource poolconfigured by the eNB to which a connection is reestablishedsuccessfully by the UE; and before the UE receives the resource pool ofmode 2 configured by the eNB to which a connection is reestablishedsuccessfully by the UE, the first selection unit 601 selects theresource for D2D communication from the resource pool of mode 2configured by the eNB where the failure occurs.

In this embodiment, the apparatus 600 further includes:

a first releasing unit 602 configured to release the resource pool afterthe UE receives the first resource allocated in the first mode by thesecond eNB, or when the UE receives from the second eNB indicationinformation indicating the UE to use the first resource.

In an implementation, when the UE performs inter-cell handover, afterthe UE receives the resource of mode 1 allocated by the target eNB, theMAC layer will be configured with the resource of mode 1, and the firstreleasing unit 602 releases the resource of mode 2; or, when the UEreceives the indication information of the target eNB indicating the UEto use the resource of mode 1, the use of the resource of mode 2 isterminated, the first releasing unit 602 releases the resource of mode2, and requests the target cell for the resource of mode 1.

In an implementation, when the UE performs failure reestablishment,after the UE receives the resource of mode 1 allocated by the eNB towhich a connection is reestablished successfully by the UE, the MAClayer will be configured with the resource of mode 1, and the firstreleasing unit 602 releases the resource of mode 2; or, when the UEreceives the indication information of the eNB to which a connection isreestablished successfully by the UE indicating the UE to use theresource of mode 1, the use of the resource of mode 2 is terminated, thefirst releasing unit 602 releases the resource pool of mode 2, andrequests the eNB to which a connection is reestablished successfully bythe UE for the resource of mode 1.

In this embodiment, if a time used by the UE in succeeding in handoveris relatively short, in a relatively short process of handover, it ispossible that the resource pool configured in the second mode is notused. Hence, the apparatus 600 may further include:

a first setting unit 603 configured to set a first predetermined time,the first predetermined time being shorter than a time from the UEreceives the configuration information to the UE is connectedsuccessfully to the second eNB;

and when the UE is handed over to the second eNB unsuccessfully withinthe first predetermined time starting from the UE receives theconfiguration information, the second period includes a period fromexceeding the first predetermined time until the first resource isreceived.

In this embodiment, if a time used by the UE in a reestablishmentprocess is relatively short, in a relatively short reestablishmentprocess, it is possible that the resource pool configured in the secondmode is not used. Hence, the apparatus 600 may further include:

a second setting unit 604 configured to set a second predetermined time,the second predetermined time being shorter than a time from the UEinitializes the reestablishment to the UE selects an appropriate cell;

and when the UE does not select an appropriate cell in the secondpredetermined time starting from initializing the reestablishment, thethird period includes a period from exceeding the second predeterminedtime until the first resource is received.

In this embodiment, the apparatus may further include:

a receiving unit 605 configured to receive configuration informationreconfigured by the first eNB;

wherein, the configuration information includes: a time-frequencylocation of the resource pool configured in the second mode by thesecond eNB, and/or information indicating whether the second eNBsupports a resource allocation scheme in the first mode, and/or aresource location of a resource allocated in the first mode by thesecond eNB.

In this embodiment, the first releasing unit 602, the first setting unit603, the second setting unit 604 and the receiving unit 605 areoptional.

In this embodiment, the first period, the second period, the thirdperiod and the fourth period are as described in embodiments 1-3, andshall not be described herein any further.

It can be seen from the above resource selection apparatus of thisembodiment that the UE may use the resource selected from the resourcepool configured by the first eNB or the second eNB in the second modefor communication in a prescribed period, which facilitates the UE toselect a corresponding resource for the D2D communication in a handoverscenario or a failure reestablishment scenario, so as to ensurecontinuity of the D2D communication.

Embodiment 5

Embodiment 5 of the present invention provides UE, including theresource selection apparatus as described in Embodiment 4.

FIG. 7 is a block diagram of a structure of the UE 700 of the embodimentof the present invention. As shown in FIG. 7, the UE 700 may include acentral processing unit 701 and a memory 740, the memory 740 beingcoupled to the central processing unit 701. It should be noted that thisfigure is illustrative only, and other types of structures may also beused, so as to supplement or replace this structure and achievetelecommunications function or other functions.

In an implementation, the functions of the resource selection apparatusmay be integrated into the central processing unit 701. Wherein, thecentral processing unit 701 may be configured to:

select a resource for performing device to device (D2D) communicationfrom a resource pool configured in a second mode by a first eNB or asecond eNB after user equipment (UE) is disconnected from the first eNB,in a first period from the UE receives physical layerout-of-synchronization indication information to the UE receives a firstresource allocated in a first mode by the second eNB reestablishing aconnection with the UE, or in a second period from the UE receivesconfiguration information triggering the UE to be handed over to thesecond eNB to the UE receives a first resource allocated in a first modeby the second eNB, or in a third period from the UE initializesreestablishment to the UE receives a first resource allocated in a firstmode by the second eNB reestablishing a connection with the UE, or in afourth period from the UE transmits a reestablishment request to the UEreceives a first resource allocated in a first mode by the second eNBreestablishing a connection with the UE.

Wherein the first resource allocated in the first mode and the resourcepool configured in the second mode are as described in embodiments 1-4,and shall not be described herein any further.

In an implementation, the central processing unit 701 may be configuredto: select the resource for performing the communication from a resourcepool configured in a second mode by the second eNB, after the UEreceives the resource pool configured in the second mode by the secondeNB; and select the resource for performing the communication from aresource pool configured in the second mode by the first eNB, before theUE receives the resource pool configured in the second mode by thesecond eNB.

In an implementation, the central processing unit 701 may be configuredto: release the resource pool after the UE receives the first resourceallocated in the first mode by the second eNB, or when the UE receivesfrom the second eNB indication information indicating the UE to use thefirst resource.

In an implementation, the central processing unit 701 may be configuredto: when the UE is handed over to the second eNB unsuccessfully within afirst predetermined time starting from the UE receives the configurationinformation, the second period includes a period from exceeding thefirst predetermined time until the first resource is received;

the first predetermined time is shorter than a time from the UE receivesthe configuration information to succeeding in being connected to thesecond eNB.

In an implementation, the central processing unit 701 may be configuredto: when the UE does not select an appropriate cell in a secondpredetermined time starting from initializing the reestablishment, thethird period includes a period from exceeding the second predeterminedtime until the first resource is received;

the second predetermined time is shorter than a time starting fromreestablishment initialization to that an appropriate cell is selected.

In another implementation, the resource selection apparatus and thecentral processing unit 701 may be configured separately. For example,the resource selection apparatus may be configured as a chip connectedto the central processing unit 701 (such as a resource selecting unit750), with its functions being realized under control of the centralprocessing unit.

As shown in FIG. 7, the UE 700 may further include a communicationmodule 710, an input unit 720, an audio processing unit 730, a display760 and a power supply 770. It should be noted that the UE 700 does notnecessarily include all the parts shown in FIG. 7. And furthermore, theUE 700 may include components not shown in FIG. 7, and the prior art maybe referred to.

As shown in FIG. 7, the central processing unit 701 is sometimesreferred to as a controller or control, and may include a microprocessoror other processor devices and/or logic devices. The central processingunit 701 receives input and controls operations of every components ofthe UE 700.

Wherein, the memory 740 may be, for example, one or more of a buffermemory, a flash memory, a hard drive, a mobile medium, a volatilememory, a nonvolatile memory, or other suitable devices, which may storethe above information on failures. Furthermore, it may store programsexecuting related information. And the central processing unit 701 mayexecute the programs stored in the memory 740, so as to realizeconfiguration information and reconfiguration information storage, etc.Functions of other parts are similar to those of the prior art, whichshall not be described herein any further. The parts of the UE 700 maybe realized by specific hardware, firmware, software, or any combinationthereof, without departing from the scope of the present invention.

It can be seen from the above UE of this embodiment that the UE may usethe resource selected from the resource pool configured by the first eNBor the second eNB in the second mode for communication in a prescribedperiod, which facilitates the UE to select a corresponding resource forthe D2D communication in a handover scenario or a failurereestablishment scenario, so as to ensure continuity of the D2Dcommunication.

Embodiment 6

Embodiment 6 of the present invention provides a resource selectionapparatus. FIG. 8 is a schematic diagram of a structure of the resourceselection apparatus of this embodiment. As shown in FIG. 8, the resourceselection apparatus 800 includes:

a first transmitting unit 801 configured to transmit a handover requestto a second eNB according to a measurement result transmitted by UE, thehandover request including information on that the UE is performing D2Dcommunication, and/or an allocation mode and a resource location of aD2D communication resource used by the UE;

a first receiving unit 802 configured to receive configurationinformation fed back by the second eNB according to the handoverrequest, the configuration information including a time-frequencylocation of a resource pool configured in a second mode by the secondeNB, and/or information indicating whether the second eNB supports aresource allocation scheme in a first mode, and/or a resource locationof a resource allocated in the first mode by the second eNB; and

a first configuring unit 803 configured to reconfigure the configurationinformation for the UE.

By reconfiguring the configuration information by the resource selectionapparatus for the UE, the UE may use the resource selected from theresource pool configured by the first eNB or the second eNB in thesecond mode for communication in a prescribed period, which facilitatesthe UE to select a corresponding resource for the D2D communication in ahandover scenario or a failure reestablishment scenario, so as to ensurecontinuity of the D2D communication.

Embodiment 7

Embodiment 7 of the present invention provides an eNB, including theresource selection apparatus as described in Embodiment 6.

FIG. 9 is a block diagram of a structure of the eNB of the embodiment ofthe present invention. As shown in FIG. 9, the eNB 900 may include acentral processing unit (CPU) 901 and a memory 910, the memory 910 beingcoupled to the central processing unit 901. Wherein, the memory 910 maystore various data, and furthermore, it may store programs for resourceselection, and execute the programs under control of the centralprocessing unit 901, so as to receive a measurement result transmittedby the UE, etc., and transmit configuration information, etc., to theUE.

In an implementation, the functions of the resource selection apparatusmay be integrated into the central processing unit 901. Wherein, thecentral processing unit 901 may be configured to: transmit a handoverrequest to a second eNB according to a measurement result transmitted byUE, the handover request including information on that the UE isperforming D2D communication, and/or an allocation mode and a resourcelocation of a D2D communication resource used by the UE; receiveconfiguration information fed back by the second eNB according to thehandover request, the configuration information including atime-frequency location of a resource pool configured in a second modeby the second eNB, and/or information indicating whether the second eNBsupports a resource allocation scheme in a first mode, and/or a resourcelocation of a resource allocated in the first mode by the second eNB;and reconfigure the configuration information for the UE.

In another implementation, the resource selection apparatus and thecentral processing unit may be configured separately. For example, theresource selection apparatus may be configured as a chip connected tothe central processing unit 901 (such as a resource selecting unit 940),with its functions being realized under control of the centralprocessing unit. Furthermore, as shown in FIG. 9, the eNB 900 mayfurther include a transceiver 920, and an antenna 930, etc.; wherein,functions of the above components are similar to those in the prior art,and shall not be described herein any further. It should be noted thatthe eNB 900 does not necessarily include all the parts shown in FIG. 9.And furthermore, the eNB 900 may include components not shown in FIG. 9,and the prior art may be referred to.

By reconfiguring the configuration information by the eNB of thisembodiment for the UE, the UE may use the resource selected from theresource pool configured by the first eNB or the second eNB in thesecond mode for communication in a prescribed period, which facilitatesthe UE to select a corresponding resource for the D2D communication in ahandover scenario or a failure reestablishment scenario, so as to ensurecontinuity of the D2D communication.

Embodiment 8

Embodiment 8 of the present invention provides an eNB. FIG. 10 is aschematic diagram of a structure of the eNB of the embodiment of thepresent invention. As shown in FIG. 10, the eNB 1000 may include acentral processing unit (CPU) 1001 and a memory 1010, the memory 1010being coupled to the central processing unit 1001. Wherein, the memory1010 may store various data, and furthermore, it may store programs forresource selection, and execute the programs under control of thecentral processing unit 1001, so as to receive a handover requesttransmitted by the source eNB, etc., and transmit configurationinformation, etc., to the source eNB.

In an implementation, the central processing unit 1001 may be configuredto: receive a handover request transmitted by a first eNB, the handoverrequest including information on that the UE is performing D2Dcommunication, and/or an allocation mode and a resource location of aD2D communication resource used by the UE, and feed back configurationinformation according to the handover request, the configurationinformation including a time-frequency location of a resource poolconfigured in a second mode by the second eNB, and/or informationindicating whether the second eNB supports a resource allocation schemein a first mode, and/or a resource location of a resource allocated inthe first mode by the second eNB.

In an implementation, the central processing unit 1001 may further beconfigured to: notify the UE of a first resource allocated by the secondeNB in the first mode.

In an implementation, the central processing unit 1001 may further beconfigured to: transmit indication information indicating the UE to usethe first resource allocated by the second eNB in the first mode, sothat the UE releases the resource pool.

In another implementation, the resource selection apparatus and thecentral processing unit may be configured separately. For example, theresource selection apparatus may be configured as a chip connected tothe central processing unit 1001 (such as a resource selecting unit1040), with its functions being realized under control of the centralprocessing unit. Furthermore, as shown in FIG. 10, the eNB 1000 mayfurther include a transceiver 1020, and an antenna 1030, etc.; wherein,functions of the above components are similar to those in the prior art,and shall not be described herein any further. It should be noted thatthe eNB 1000 does not necessarily include all the parts shown in FIG.10. And furthermore, the eNB 1000 may include components not shown inFIG. 10, and the prior art may be referred to.

With the eNB of this embodiment, the UE may use the resource selectedfrom the resource pool configured by the first eNB or the second eNB inthe second mode for communication in a prescribed period, whichfacilitates the UE to select a corresponding resource for the D2Dcommunication in a handover scenario or a failure reestablishmentscenario, so as to ensure continuity of the D2D communication.

Embodiment 9

FIG. 11 is a schematic diagram of a structure of the communicationsystem of Embodiment 9 of the present invention. As shown in FIG. 11,the communication system 1100 includes UE 1101, a first eNB 1102 and asecond eNB 1103, wherein, after the UE 1101 is disconnected from thefirst eNB 1102, the UE 1101 selects a resource for performing D2Dcommunication from a resource pool configured in a second mode by thefirst eNB 1102 or the second eNB 1103, in a first period from the UE1101 receives physical layer out-of-synchronization indicationinformation to the UE receives a first resource allocated in a firstmode by the second eNB 1103 reestablishing a connection with the UE, orin a second period from the UE 1101 receives configuration informationtriggering the UE 1101 to be handed over to the second eNB 1103 to theUE 1101 receives a first resource allocated in a first mode by thesecond eNB 1103, or in a third period from the UE 1101 initializesreestablishment to the UE 1101 receives a first resource allocated in afirst mode by the second eNB 1103 reestablishing a connection with theUE 1101, or in a fourth period from the UE 1101 transmits areestablishment request to the UE 1101 receives a first resourceallocated in a first mode by the second eNB 1103 reestablishing aconnection with the UE 1101.

In this embodiment, allocating the first resource in the first mode andallocating the resource pool in the second mode by the eNBs are asdescribed in the above embodiments, and shall not be described hereinany further.

In this embodiment, when the failure of triggering the initializationreestablishment process is a radio link failure (RLF), the UE 1101selects the resource for D2D communication from the resource poolconfigured by the first eNB or the second eNB in the second mode in thefirst period (T1) from the UE 1101 receives the physical layerout-of-synchronization indication information to the UE receives thefirst resource allocated in the first mode by the second eNBreestablishing a connection with the UE 1101, but does not use the firstresource configured by the eNB in the first mode.

In this embodiment, when the failure of triggering the initializationreestablishment process is a handover failure, the UE 1101 selects theresource for D2D communication from the resource pool configured by thefirst eNB or the second eNB in the second mode in the second period (T2)from the UE 1101 receives the configuration information triggering theUE 1101 to be connected to the second eNB to the UE 1101 receives thefirst resource allocated in the first mode by the second eNB, but doesnot use the first resource configured by the eNB in the first mode.

In this embodiment, when the failure of triggering the initializationreestablishment process is an eNB reconfiguration failure, an underlyingintegrity check failure, or a handover failure, the UE 1101 selects theresource for D2D communication from the resource pool configured by thefirst eNB or the second eNB in the second mode in the third period (T3)from the UE 1101 initializes the reestablishment to the UE 1101 receivesthe first resource allocated in the first mode by the second eNBreestablishing a connection with the UE 1101, but does not use the firstresource configured by the eNB in the first mode.

In this embodiment, when the failure of triggering the initializationreestablishment process is a handover failure, the UE 1101 selects theresource for D2D communication from the resource pool configured by thefirst eNB or the second eNB in the second mode in the fourth period (T4)from the UE 1101 transmits the reestablishment request to the UE 1101receives the first resource allocated in the first mode by the secondeNB reestablishing a connection with the UE 1101, but does not use thefirst resource configured by the eNB in the first mode.

After the UE receives the configuration information triggering the UE tobe connected to the second eNB, the UE 1101 is disconnected from thefirst eNB, and establishes a connection with the second eNB via a randomaccess process. The UE 1101 selects the resource for D2D communicationfrom the resource pool configured by the first eNB or the second eNB inthe second mode in the second period (T2) from the UE 1101 receives theconfiguration information triggering the UE 1101 to be connected to thesecond eNB to the UE receives the first resource allocated in the firstmode by the second eNB, but does not use the first resource configuredby the eNB in the first mode.

After receiving the resource pool configured by the second eNB in thesecond mode, the UE 1101 selects the resource for D2D communication fromthe resource pool configured by the second eNB; and before receiving theresource pool configured by the second eNB in the second mode, the UE1101 selects the resource for D2D communication from the resource poolconfigured by the first eNB in the second mode.

In this embodiment, after receiving the first resource allocated by thesecond eNB in the first mode, or when receiving the indicationinformation of the second eNB indicating the UE to use the firstresource, the UE 1101 releases the resource pool.

In this embodiment, if a time used by the UE 1101 in succeeding inhandover is relatively short, in a relatively short process of handover,it is possible that the resource pool configured in the second mode isnot used. Hence, the method may further include: when the UE 1101 ishanded over to the second eNB unsuccessfully within a firstpredetermined time starting from the UE 1101 receives thereconfiguration information, the second period includes a period fromexceeding the first predetermined time until the first resource isreceived; wherein, the first predetermined time is shorter than a timefrom the UE 1101 receives the configuration information to succeeding inbeing connected to the second eNB.

In this embodiment, if a time used by the UE 1101 in a reestablishmentprocess is relatively short, in a relatively short reestablishmentprocess, it is possible that the resource pool configured in the secondmode is not used. Hence, the method may further include: when the UE1101 does not select an appropriate cell within a second predeterminedtime starting from initializing the reestablishment, the third periodincludes a period from exceeding the second predetermined time until thefirst resource is received; wherein, the second predetermined time isshorter than a time starting from reestablishment initialization to thatan appropriate cell is selected. In this embodiment, Embodiment 5 may bereferred to for a construction of the UE 1101, the contents of whichbeing incorporated herein, and being not going to be described hereinany further.

In this embodiment, the first eNB 1102 is further configured to transmita handover request to the second eNB 1103 according to a measurementresult transmitted by UE, the handover request including information onthat the UE is performing D2D communication, and/or an allocation modeand a resource location of a D2D communication resource used by the UE,and receive configuration information fed back by the second eNB 1103according to the handover request, the configuration informationincluding a time-frequency location of a resource pool configured in asecond mode by the second eNB 1103, and/or information indicatingwhether the second eNB supports a resource allocation scheme in a firstmode, and/or a resource location of a resource allocated in the firstmode by the second eNB 1103.

In this embodiment, the first eNB 1102 is further configured toconfigure the configuration information for the UE 1101.

In this embodiment, Embodiment 7 may be referred to for a constructionof the eNB 1102, the contents of which being incorporated herein, andbeing not going to be described herein any further.

In this embodiment, the second eNB 1103 is further configured to receivethe handover request transmitted by the first eNB 1102, the handoverrequest including information on that the UE 1101 is performing D2Dcommunication, and/or an allocation mode and a resource location of aD2D communication resource used by the UE 1101, and feed back theconfiguration information to the first eNB 1102 according to thehandover request, the configuration information including atime-frequency location of a resource pool configured in a second modeby the second eNB 1103, and/or information indicating whether the secondeNB 1103 supports a resource allocation scheme in a first mode, and/or aresource location of a resource allocated in the first mode by thesecond eNB 1103.

In this embodiment, the second eNB 1103 is further configured to notifythe resource allocated in the first mode to the UE 1101.

In this embodiment, the second eNB 1103 is further configured totransmit indication information indicating the UE 1101 to use the firstresource allocated in the first mode, so that the UE 1101 releases theresource pool.

In this embodiment, Embodiment 8 may be referred to for a constructionof the second eNB 1103, the contents of which being incorporated herein,and being not going to be described herein any further.

In this embodiment, the communication system may further include otherUE (not shown), and the UE 1101 uses the resource of mode within theabove prescribed periods for performing D2D communication with the otherUE.

An embodiment of the present invention provides a computer-readableprogram, wherein when the program is executed in a resource selectionapparatus or UE, the program enables a computer to carry out theresource selection method as described in Embodiment 1 or 2 or 3 in theapparatus or UE.

An embodiment of the present invention further provides a storage mediumin which a computer-readable program is stored, wherein thecomputer-readable program enables a computer to carry out the resourceselection method as described in Embodiment 1 or 2 or 3 in a resourceselection apparatus or UE.

The above apparatuses and methods of the present invention may beimplemented by hardware, or by hardware in combination with software.The present invention relates to such a computer-readable program thatwhen the program is executed by a logic device, the logic device isenabled to carry out the apparatus or components as described above, orto carry out the methods or steps as described above. The presentinvention also relates to a storage medium for storing the aboveprogram, such as a hard disk, a floppy disk, a CD, a DVD, and a flashmemory, etc.

The present invention is described above with reference to particularembodiments. However, it should be understood by those skilled in theart that such a description is illustrative only, and not intended tolimit the protection scope of the present invention. Various variantsand modifications may be made by those skilled in the art according tothe spirits and principle of the present invention, and such variantsand modifications fall within the scope of the present invention.

What is claimed is:
 1. A base station comprising: a transceiverconfigured to: transmit a handover request to another base stationaccording to a measurement result received from a terminal, the handoverrequest comprising information that the terminal is performing D2Dcommunication, and an allocation mode and a resource location of a D2Dcommunication resource used by the terminal; receive configurationinformation fed back from the another base station according to thehandover request, the configuration information comprising atime-frequency location of a resource pool for the terminal to select aresource for D2D communication to be used in a second mode in a cell ofthe another base station; and a resource location of a resource to beused in a first mode in the cell of the another base station; andprocessor circuitry configured to: configure the configurationinformation in the terminal.
 2. The base station according to claim 1,the configuration information further comprising information indicatingwhether the another base station supports a resource allocation schemein the first mode, and a resource location of a resource used in thefirst mode in the cell of the another base station.
 3. A communicationsystem, comprising a first base station, a second base station and aterminal, wherein, the first base station is configured to transmit ahandover request to the second base station according to a measurementresult transmitted by the terminal, the handover request comprisinginformation that the terminal is performing D2D communication, and anallocation mode and a resource location of a D2D communication resourceused by the terminal, and receive configuration information fed backfrom the second base station according to the handover request, theconfiguration information comprising: a time-frequency location of aresource pool for the terminal to select a resource for D2Dcommunication to be used in a second mode in a cell of the second basestation; and a resource location of a resource to be used in a firstmode in the cell of the second base station; the first base station isfurther configured to configure the configuration information in theterminal; and processor circuitry in the terminal is configured toselect the resource for D2D communication used in the second mode amongthe first mode and the second mode in the cell of the second basestation.
 4. The communication system according to claim 3, theconfiguration information further comprising information indicatingwhether the second base station supports a resource allocation scheme inthe first mode, and a resource location of a resource used in the firstmode in the cell of the second base station.
 5. A terminal comprising: atransmitter configured to transmit to a first base station a signalincluding a measurement result; and, a receiver configured to receive aconfiguration information from a second base station via the first basestation, the configuration information including a time-frequencylocation of a resource pool for the terminal to select a resource forD2D communication used in a second mode, and/or a resource location of aresource used in a first mode in the cell of the second base station;and processor circuitry in the terminal configured to select theresource for D2D communication used in the second mode among the firstmode and the second mode when the configuration information includes thetime-frequency location used in the second mode.
 6. The terminalaccording to claim 5, the configuration information further comprisinginformation indicating whether the second base station supports aresource allocation scheme in the first mode, and a resource location ofa resource used in the first mode in the cell of the second eNB.